This invention relates to a coolable electrical component and, more particularly, to a high voltage electrical transmission system which is provided with a cooling apparatus.
A cooled transmission system of this type is described, for example, in European Patent Application No. 0,048,126. The transmission system or the electrical bus, as it is also known, described therein is a tubular gas cable which has a grounded housing and which is filled with an insulating gas. A conductor of hollow cylindrical construction carrying a high tension voltage is arranged within the housing and is insulated therefrom by means of insulating spacers. The conductor is provided with passage orifices which allow insulating gas present in its interior and in the annular chamber space between housing and the conductor to pass therethrough. At least one gas outlet orifice through which heated insulating gas is passed out of the interior of the conductor and through an insulator cylinder into a cooling apparatus is located outside the housing. Cooled gas is passed through a channel annularly surrounding the insulator cylinder into the annular chamber, where, in order to cool the conductor, it is passed first to the external surface of the conductor and then, after passing through the passage orifices, along its internal surface to the outlet orifice.
Although it is possible with this tubular gas cable to increase the current load capacity of the electrical bus by up to 60%, in comparison to an uncooled cable of the same size, nevertheless due to the comparatively inefficient cooling action of the insulating gas, which operates by convection current only, it is necessary to provide numerous cooling apparatuses at closely spaced intervals of the cable. Additionally, the internal surface of the conductor must be enlarged, for example by milling surface grooves therein. These measures are quite burdensome and further create an undesirably large structure requiring more space.